Hey Guys, I have a older 775 board that I am using in LAN party/Hackintosh. It is running a Q8300 (2.5 Ghz) at 3.0Ghz at 1.25 volts. The ram is running at 800Mhz (stock, using 2.1 volts) with all timings set to defaults. It all works great while I am running a green/eco 9800 GT. I recently tried switching to a 4850 I had kicking around and the system would not even boot (bios beep errors indicated ram failure) unless I went back to stock settings. Any ideas on why this would happen? All power cables were connected properly and when at stock settings the 4850 ran fine.

What power supply are you using on that system? You don't have a s775 system in your signature which is why im asking.

Sorry for the late reply. The 4850 is not overclocked (but it is passive). I totally forgot about the PCI-e frequency and I will try that first. I have a feeling it is the PSU since it is just a cheap OCZ steathextreme 500 watter I picked up for $30 on sale. I grabbed it since I have a SFF case and the stealthextreme has completely modular cables. I will try the PCI-e frequency first and then switch the PSU if that doesn't work.

P.S. Coffaholic, If you check my sig you will see my main rig is a 775 but that is not the system I am talking about

Looks like locking the PCI-e frequency did nothing. Going to have to try switching out the PSU to see if that helps. System runs rock stable with 9800GT eco (no additional power required) but as soon as I put in the 4850 I get no post and bios beeps indicate a memory issue.

Well, now I finally got around to changing the power supply (antec 550 mid level PSU) and I am still having the same problem. The system will boot overclocked just fine from a cold boot and is rock stable, but when I restart I get bios beeps telling me there is a memory problem. I tried upping the CPU voltage a tad and the memory voltage a tad but as soon as I reboot I get the same problem and I have to power off and boot using standard clocks.